10 LET A=32767
15 LET D=32766
20 POKE A,7
25 POKE D,255-8
30 FOR F=0 TO 15
35 POKE A,6
40 POKE D,32-F*2
45 POKE A,8
50 POKE D,15-F
55 FOR G=0 TO 25
60 NEXT G
65 NEXT F
